You can use this module for controlling your circuit with light. Light sensor sends signal to output according to light intensity. In “light” mode, as the light shining on the sensor gets brighter, more signal passes through it. In “dark” mode, the signal increases as it gets darker. You can use the light mode for making alarm that rings in the sunrise. By using dark mode, you can make a lamp that automatically lights up when it is dark in the night. Also, you can adjust the sensitivity with dimmer on the module. If you turn it in the ‘+’ direction, the circuit become more sensitive to light.